Under the United Nations Framework Convention on Climate Change (UNFCCC), countries negotiate how to address the impacts of anthropogenic climate change through mitigation and adaptation. Despite these efforts, climate-related events still cause huge impacts across the globe every year. Impacts can be particularly devastating in developing countries and this is what the relatively new area of ‘loss and damage’ in the negotiations aims to address.

In 2013, the UNFCCC established the Warsaw International Mechanism (WIM) to “address loss and damage associated with impacts of climate change, including extremes events and slow onset events, in developing countries that are particularly vulnerable to the adverse effects of climate change” (UNFCCC, 2013). Two decades of negotiating went into forming this mechanism, since the first calls from small island developing states in the early 1990s to address the effects of sea level rise.

Island states such as Vanuatu in the South Pacific have been requesting support for the impacts of sea level rise since the early 1990s. Source: Meredith James/Flickr/CC BY-NC-ND 2.0

The WIM states it will address the impacts of both extreme events (such as floods and heatwaves) and slow onset events (such as sea level rise). However, as yet, there is no official definition of what loss and damage will actually encompass. In our commentary in Nature Climate Change (James et al., 2014), we considered one aspect of defining loss and damage: whether loss and damage would need to be attributed to anthropogenic climate change. As the text of the WIM describes “loss and damage associated with the impacts of climate change” and the UNFCCC’s definition of climate change is that which is “attributed directly or indirectly to human activity” (UNFCCC, 1992), this could imply that there would need to be proof that impacts from events were caused by anthropogenic climate change.

If this were the case, impacts would first need to be attributed to particular events (e.g. the infrastructure damaged by a particular flood), and then the event would need to be attributed to anthropogenic climate change. For slow-onset events like sea level rise, the science attributing these to anthropogenic climate change is well-established. However for individual events it is much more challenging to say how climate change had an influence. Extreme event attribution can, for some types of events, estimate how anthropogenic climate change affected the probability of the particular event occurring. This generally relies on large ensembles of climate model simulations, which are necessary to estimate the probabilities of such rare events, and studies therefore rely on the ability of the models to represent the processes that produce the extreme event in question. Observations are also necessary to both to validate the model simulations and define the extreme event to be studied, which are not always available, particularly in developing countries. Up to now, studies attributing specific events have been carried out on an ad hoc basis in the aftermath of particularly extreme events, rather than more systematically. They have also mainly focussed on events in developed countries, rather than the developing countries the WIM aims to assist.

Typhoon Haiyan caused devastation in November 2013 as the WIM was being negotiated. It was used as an example of loss and damage, but without any consideration of whether anthropogenic climate change played a role. Is this an important consideration? Source: DFID/Flickr/CC BY 2.0

While the attribution of events to anthropogenic climate change could be relevant to addressing loss and damage, it is controversial in negotiations. This is in part due to its perceived association with compensation claims. However we suggest that, somewhere along the line, the question of causality is likely to come up, to establish just what the loss and damage being addressed is. Attribution may or may not have a role to play here. What is key is that as event attribution science is continuing to develop, scientists and policymakers need to have opportunities for conversations about what information the science can provide and how this could be applied if it was deemed necessary for policy.

Since writing our commentary we have continued to research this science-policy interface. We have investigated what is understood about event attribution science by stakeholders associated with loss and damage negotiations and how they think it could be relevant (Parker et al., 2016). We have also investigated how policymakers and practitioners are defining ‘loss and damage’, as this still has no official definition and there are differing perspectives among those looking to address loss and damage. Our aim is that by better understanding this policy context, the science will be able to develop in ways that are most relevant to the needs of decision makers and, if deemed relevant, ultimately help to address loss and damage in vulnerable regions.

This work forms part of the ACE-Africa project, for more information see http://www.walker.ac.uk/projects/ace-africa-attributing-impacts-of-external-climate-drivers-on-extreme-weather-in-africa/